Electrocardiography in Various Settings
European Cardiovascular Disease 2006 - Issue 1;2006:2(1):1-3
Currently, the routine procedure for investigation of subjective cardiac complaints is recording of the electrical activity of the heart by means of an electrocardiograph (ECG). The most basic version is a rhythm strip on one to three channels. This procedure normally requires time-consuming preparation of the patient to position the electrodes and initiate proper equipment settings. Especially in patients with paroxysmal complaints, the chance of finding cardiac events is quite low.
Further investigation is normal, depending on the degree of occurrence of complaints, and these patients will usually be referred to secondary care. Standard 12-lead ECG, and even exercise ECG, is not always conclusive, and this means that continuous monitoring by a 24-hour Holter or event recorder is necessary. The irregular nature of the cardiac complaints, however, can cause even these diagnostic procedures to be unsuccessful. Personal home ECG monitoring may in these cases be the only tool suitable for medical professionals to set an accurate diagnosis.
Subjective Cardiac Complaints
Cardiac complaints can be suspected when patients have symptoms such as palpitations, chest pain, temporary loss of consciousness, breathlessness, etc. Unexplained dizziness and falling can also be indicators of cardiac problems. The often-irregular occurrence and fuzzy complaint description should lead to further investigation of the cardiac function.
Patients with these complaints will initially be palpitated to investigate the regularity of the heart rhythm and the strength of the heartbeat. Deviations in the heart rhythm have to be readily detectable in a short period of time because not all health professionals will check for a full minute.
The preparation time for an ECG rhythm strip on a conventional ECG device with chest electrode is widely regarded as a burden in daily practice. The interpretation of the ECG information is the second restriction for proper diagnosis in primary care. Medical professionals do not always accept computer evaluation software. The third and usually most relevant restriction is the fact that symptoms are not occurring during this investigation. Referral to secondary care is in these cases the only option.
Patients referred from primary care will in most cases again be subject to ECG monitoring. In secondary care, the heart activity will be reassessed using more sophisticated equipment and software. The chance of symptoms occurring during this investigation is similar to the investigation in primary care.
Initially, a closer look at the heart activity will be taken by means of an ECG on more channels. A 12-lead ECG will provide more information on the heart activity and will find those patients where structural problems are present. In patients where the symptoms are irregular, this investigation will show no abnormal electrical activity.
To determine whether the complaints are related to the stress the heart encounters upon physical activity, it is possible to take an ECG reading during exercise. Here, the patient will be asked to walk on a treadmill while connected to an ECG device. In some patients, this will induce electrical abnormalities and these will be recorded on the ECG device.
Patients showing no abnormalities will need further investigation by means of ambulatory monitoring of the heart activity.
The Holter Device
The standard procedure for ambulatory monitoring of the heart signal is done by continuously wearing a portable ECG device (on the waist). These are called Holter devices or monitors and will usually record the ECG signal for 24 or 48 hours. During this period, the patient should not deviate from their usual lifestyle. The problem is that the patient is aware of wearing the device because of the electrodes and wiring attached to the chest. The system is especially vulnerable because the electrodes can come loose from the chest and the wiring can break during the period it is being used. These devices require significant maintenance and the success rate for catching a cardiac event is quite low. The processing of the data obtained with this device is also labour-intensive.
External Event Recorder (Loop Recorder)
Another system for ambulatory monitoring is the event monitor. This is similar to the Holter device, and is also worn externally on the waist, but it only stores cardiac events when they are detected. The device continuously loops the ECG signal and will delete standard ECG data. As soon as the internal software detects a cardiac event, the data from a few minutes before until a few minutes after the event will be saved. However, the same drawbacks of the Holter device apply to this one.
Since the device does not store standard ECG information, the evaluation of the results is simpler. Usually, the device will rather store false positive readings instead of deleting false negatives. The advantage is that the device also stores the ECG information leading up to the event. The equipment main disadvantage is its price and the unwillingness of a certain percentage of patients to wear it continuously.
Invasive Event Recorder
In patients suffering from syncope, temporary loss of consciousness and long periods between symptoms, implantable event recorders are sometimes recommended. Placing the recorder requires a minor invasive procedure. There is no difference in function when compared with the external loop recorder. The advantage is that patient compliance is not an issue, but due to the invasive procedure there are price implications.
With the increase of IT, new developments are being introduced in the field of remote patient monitoring. The registration of ECG in remote situations by means of recorders with incorporated telecommunication function is becoming more common. The regulatory requirements on patient confidentiality with regard to health-related data are less of an issue due to new encryption protocols. The benefit of these systems is mainly found in the accessibility of the data when required by the healthcare provider. The use of these devices is dependant on national/local healthcare systems having the facilities in place to utilise the system. For the data obtained with such systems, it is still necessary for a medical professional to evaluate the results. For monitoring cardiac patients, these devices may very well be a step forward.
New ECG Monitor Concept HeartScan
The HeartScan offers an addition or alternative to the above-mentioned procedures:
· The HeartScan is intended for screening and self-monitoring of cardiac events (under professional supervision).
· The device can record about 30 seconds of heart rhythm and waveform each time it is activated.
· After recording, the automatic evaluation software will check the collected data.
· Directly after completing the measurement, the recorded rhythm strip can be reviewed on the LCD screen.
· For further evaluation, the data can be transferred to a PC screen with the ECG-viewer software.
· The SD memory card can store up to 300 recordings, offering sufficient space for long-term monitoring.
· The HeartScan is simple to operate.
· The HeartScan is portable (similar in size and weight to a mobile phone).
· The HeartScan is cordless (there are no electrodes or lead wires).
Heart Scan in Primary Care
In primary care, the HeartScan ECG Monitor offers a fast way to pre-screen patients in the office when presenting with possible CVD-related complaints. Instead of palpitation, the device can give a clear picture of the heart rhythm in only 30 seconds. The device can show events such as extra systoles, premature ventricular contractions, supraventricular premature contractions and ST-level deviations.
The portability of the device makes it suitable to use for home visits. The direct on-screen display makes it possible to evaluate the ECG without first printing or downloading the reading.
Worried patients without obvious CVD risk factors can use the device at home on themselves to confirm if their complaints are related to a cardiac condition.
The device can help assess the necessity of referring the patient to secondary care.
Heart Scan in Secondary Care
When after 12-lead ECG, exercise and Holter/event the complaints cannot be captured due to their transient character, the HeartScan ECG Monitor can be a valuable addition.
Instead of discharging these patients, the device can be lent out for a longer period of time to use when symptoms occur. Alternatively, the patient can be instructed to measure at regular intervals to assess circadian influences.
Where patients refuse implantation of an event recorder, this device can be a substitute. The decision to suggest the implanted recorder could be preceded by a period using the HeartScan ECG Monitor.
After diagnosis is established and the patient is prescribed medication, the HeartScan ECG Monitor can be used to check medication tolerance, efficacy and compliance. When the medication is properly dosed and the patient is complying with the medication regimen, the use of the HeartScan device can be stopped.
When hospitalised, not all patients are continually monitored for ECG function. There are several circumstances where the HeartScan would be a valuable tool for a quick scan of heart function, such as before and during dialysis, following surgery and for patients in the emergency room.
The unique features of the HeartScan ECG Monitor make this a versatile, multi-purpose tool for medical professionals. The cordless operation and direct on-screen display allows a quick scan of the heart condition and, due to its compact design, the device fits easily in a white-coat pocket or doctor.